Only a few of those comments are specifically about in-app purchasing... As I read them they nearly all criticise the value of the game / extras combination which this developer may have got wrong (it looks like in-app purchasing was added after the initial release so customers had assumed they'd bought all there was to have). My view is that - provided pricing is good value (to me) - I prefer in-app upgrades over having to download a new / replacement 'premium' app. Especially as in-app purchasing generally gives greater granularity over what can be purchased.